Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and fine vellus hair. Most common interest in hair is focused on hair growth, hair types, and hair care, but hair is also an important biomaterial primarily composed of protein, notably alpha-keratin.
In Greek mythology, Caerus was the personification of opportunity, luck and favorable moments. He was shown with only one lock of hair. His Roman equivalent was Occasio or Tempus. Caerus was the youngest son of Zeus. Caerus and Fortuna became lovers after Caerus neglected to overthrow his father as everyone thought he would.
Tonsure is the practice of cutting or shaving some or all of the hair on the scalp as a sign of religious devotion or humility. The term originates from the Latin word tonsura and referred to a specific practice in medieval Catholicism, abandoned by papal order in 1972. Tonsure can also refer to the secular practice of shaving all or part of the scalp to show support or sympathy, or to designate mourning. Current usage more generally refers to cutting or shaving for monks, devotees, or mystics of any religion as a symbol of their renunciation of worldly fashion and esteem.
Alopecia areata, also known as spot baldness, is a condition in which hair is lost from some or all areas of the body. Often, it results in a few bald spots on the scalp, each about the size of a coin. Psychological stress and illness are possible factors in bringing on alopecia areata in individuals at risk, but in most cases there is no obvious trigger. People are generally otherwise healthy. In a few cases, all the hair on the scalp is lost, or all body hair is lost. Hair loss can be permanent, or temporary. It is distinct from pattern hair loss, which is common among males.
Hair loss, also known as alopecia or baldness, refers to a loss of hair from part of the head or body. Typically at least the head is involved. The severity of hair loss can vary from a small area to the entire body. Inflammation or scarring is not usually present. Hair loss in some people causes psychological distress.
A wig is a head or hair accessory made from human hair, animal hair, or synthetic fiber. The word wig is short for periwig, which makes its earliest known appearance in the English language in William Shakespeare's The Two Gentlemen of Verona. Some people wear wigs to disguise baldness; a wig may be used as a less intrusive and less expensive alternative to medical therapies for restoring hair or for a religious reason.
The Tanner scale is a scale of physical development in children, adolescents and adults. The scale defines physical measurements of development based on external primary and secondary sex characteristics, such as the size of the breasts, genitals, testicular volume and development of pubic hair. This scale was first identified in 1969 by James Tanner, a British pediatrician, after a two-decade-long study following the physical changes in girls undergoing puberty.
A piebald or pied animal is one that has a pattern of unpigmented spots (white) on a pigmented background of hair, feathers or scales. Thus a piebald black and white dog is a black dog with white spots. The animal's skin under the white background is not pigmented.
Head shaving is a form of body modification which involves shaving the hair from a person's head. People throughout history have shaved all or part of their heads for diverse reasons including aesthetics, convenience, culture, fashion, practicality, punishment, a rite of passage, religion, or style.
The Hamilton–Norwood scale is used to classify the stages of male pattern baldness. The stages are described with a number from 1 to 7.
The management of hair loss, includes prevention and treatment of alopecia, baldness, and hair thinning, and regrowth of hair.
Trichology is the study of the hair and scalp. The term derives from Ancient Greek θρίξ (thríx), "hair" and -λογία -logia. In most jurisdictions the title of a trichologist, not the field of trichology, is considered a para-medical discipline.
Hair transplantation is a surgical technique that removes hair follicles from one part of the body, called the 'donor site', to a bald or balding part of the body known as the 'recipient site'. The technique is primarily used to treat male pattern baldness. In this minimally invasive procedure, grafts containing hair follicles that are genetically resistant to balding are transplanted to the bald scalp. Hair transplantation can also be used to restore eyelashes, eyebrows, beard hair, chest hair, pubic hair and to fill in scars caused by accidents or surgery such as face-lifts and previous hair transplants. Hair transplantation differs from skin grafting in that grafts contain almost all of the epidermis and dermis surrounding the hair follicle, and many tiny grafts are transplanted rather than a single strip of skin.
Pattern hair loss is a hair loss condition that primarily affects the top and front of the scalp. In male-pattern hair loss (MPHL), the hair loss typically presents itself as either a receding front hairline, loss of hair on the crown (vertex) of the scalp, or a combination of both. Female-pattern hair loss (FPHL) typically presents as a diffuse thinning of the hair across the entire scalp.
Snakes, like other reptiles, have skin covered in scales. Snakes are entirely covered with scales or scutes of various shapes and sizes, known as snakeskin as a whole. A scale protects the body of the snake, aids it in locomotion, allows moisture to be retained within, alters the surface characteristics such as roughness to aid in camouflage, and in some cases even aids in prey capture. The simple or complex colouration patterns are a property of the underlying skin, but the folded nature of scaled skin allows bright skin to be concealed between scales then revealed in order to startle predators.
Markings on horses are usually distinctive white areas on an otherwise dark base coat color. Most horses have some markings, and they help to identify the horse as a unique individual. Markings are present at birth and do not change over the course of the horse's life. Most markings have pink skin underneath most of the white hairs, though a few faint markings may occasionally have white hair with no underlying pink skin. Markings may appear to change slightly when a horse grows or sheds its winter coat, however this difference is simply a factor of hair coat length; the underlying pattern does not change.
The growth of human hair occurs everywhere on the body except for the soles of the feet, the inside of the mouth, the lips, the backs of the ears, the palms of the hands, some external genital areas, the navel, scar tissue, and, apart from eyelashes, the eyelids. Hair is a stratified squamous keratinized epithelium made of multi-layered flat cells whose rope-like filaments provide structure and strength to the hair shaft. The protein called keratin makes up hair and stimulates hair growth. Hair follows a specific growth cycle with three distinct and concurrent phases: anagen, catagen, and telogen. Each phase has specific characteristics that determine the length of the hair.
Bald–hairy is a common joke in Russian political discourse, referring to the empirical rule of the state leaders' succession defined as a change of a bald or balding leader to a hairy one and vice versa. This consistent pattern can be traced back to as early as 1825, when Nicholas I succeeded his late brother Alexander as the Russian Emperor. Nicholas I's son Alexander II formed the first "bald–hairy" pair of the sequence with his father.
Hair multiplication or hair cloning is a proposed technique to counter hair loss. The technology to clone hair is in its early stages. Experts previously assumed that in the case of complete baldness, follicles are completely absent from the scalp, so they cannot be regenerated. However, it was discovered that the follicles are not entirely absent, as there are stem cells in the bald scalp from which the follicles naturally arise. Abnormal behavior of these follicles is suggested to be the result of progenitor cell deficiency in these areas.
Setipiprant (INN; developmental code names ACT-129968, KYTH-105) is an investigational drug developed for the treatment of asthma and scalp hair loss. It was originally developed by Actelion and acts as a selective, orally available antagonist of the prostaglandin D2 receptor 2 (DP2). The drug is being developed as a novel treatment for male pattern baldness by Allergan.
